Mechanical stoker operable with natural draft installations



J T. NORMAN MECHANICAL STOKER OPERABLE WITH NATURAL DRAFT INSTALLATIONSFiled Feb. 15, 1939 4 Sheets-Sheet l lbflebddunl lbl eoao uocoa ei Jbs(2 1471 T/VOTmm Feb; 10, 1942 v J. T. NORMAN 2,272,813

MECHANICAL STOKER OPERABLE WITH NATURAL DRAFT' INSTALLATIONS 4 Feb. 10,1942. J, T, NORMAN 2,272,813

MECHANICAL STOKER OPERABLE WITH NATURAL DRAFT INSTALLATIONS Filed Feb.15, 1939 4 Sheets-Sheet :5

I o o a 3 Jbaeph TA/ormam/ Feb. 10, 1942. J. T.- NORMAN MECHANICALSTOKER OPERABLE WITH NATURAL DRAFT INSTALLATIONS 4 Sheets-Sheet 4 FiledFeb. 15. 1939 Patented Feb. 10, 1942 STATES PATENT OFFICE MECHANICALSTOKER OPERABLE WITH NATURAL DRAFT INSTALLATIONS Application February15, 1939, Serial No. 256,577

13 Claims.

My present invention relates to the art of stoves and furnaces, and morespecifically to that branch of the art having to do with the feeding ofcoal to the fire and the withdrawal of the ashes.

The invention has several objects in view of which the following may beinitially mentioned, namely:

To provide a stoker which will permit the use of natural (chimney) draftinstead of forced draft if desired, and thereby eliminate, so far aspossible, fly ash;

To provide a stoker which combines the advantages of an under feed withthose of an over feed stoker;

To provide a stoker that can be either anthracite or bituminous coal;

To provide a stoker which will be economical in use;

To provide a furnace grate or fire-box structure combined with amechanical stoker in' such manner that a plentiful supply of hot watermay be maintained in a tank or in the boiler for domestic and otheruses, even when the coal is not being fed to the fire, as during periodswhen the room temperature is sufliciently high and coal feed is stopped;

To provide means whereby only a portion of the grate may be suppliedwith coal, as, for instance, during mild weather or when only hot waterfor domestic use is desired;

To provide means whereby the ashes are removed from beneath the fire bedand any clinkers that may form may be broken up so as to be removable bythe ash-remover mechanism.

Other objects will in part be obvious and in part be pointed outhereinafter. 7

To the attainment of the aforesaid objects and used with ends theinvention still further resides in the novel details of construction,combination and arrangement of parts, allof which will be first fullydescribed in the following detailed description, and then beparticularly pointed out in the appended claims, reference being hadtothe ac Fig. 6 is a detail vertical longitudinal section of one of theliners of a trough.

Fig. 7 is an end elevation of the same, looking from left to right inFigs. 3 and 6.

In the drawings, in which like numerals of reference designate likeparts in all figures, I designates the end or front and back walls of afurnace fire box and ash pit, and 2 designates the side walls of thesame (or the apparatus may be made up as a separate unit to be insertedinto the fire box and ash pit space of a furnace, if

desired).

Located centrally of the box formed by the walls I and 2 is a doublewalled chamber I having a pair of centrally disposed and spacedrelatively deep vertical walls 3 joined at the bottom by asemi-cylindrical bottom wall 4. At the top the walls 3 merge withlaterally downwardly inclined walls 5 to the lower ends of which thebottom wall 6 of the receptacle is attached. The walls 3, 4, 5, 6, andend walls 1 constitute a water box or receptacle whose walls 5 lie inthe combustion zone of the ignited fuel.

The lower ends of walls 5 are connected to the inner perforated walls 8of the grates. The outer perforated walls 9 connect with theirrespective inner walls 8 via semi-cylindrical wall portions II] to forma relatively deep channel in the bottom of which may be located a lineror wear plate member 31 having a flange 38 by means of which it may besecured inplace.

Coal is fed into the channel formed by the walls 3 and 4 from the hopperor bin l6 by a continuous worm or screw I! that extends from the outerend of the hopper t0 the entrant end of the trough (at wall 4, see Fig.2). The worm terminates at the entrance to the channel so as not to feedthe coal all toward the rear of the channel. The shaft II, I! has screwor worm segments which cooperate with worm I1 and inclined bafiie I3 todistribute coal along the bottom of the channel and lift or force itupwardly Within the grate channels and a continuous worm 2| at theoutlet ends of the channels and within the ash-discharge elbows 3| Eachshaft l9 carries a gear 23 which meshes with a gear 26 on a shaft 24located above shaft 19 and below the fire-ash separation level of thefuel in the side channels of the apparatus.

The shaft 24 has worm segments 25 which serve to break up any clinkersthat may form at the bottom of the fire zone, and to feed the ashesdownwardly to the ash remover.

A chain-tightening roller 28, mounted in hangers 28 may be provided, ifdesired, and the gears 26 and 23, as well as sprocket l8, may be held ontheir respective shafts by set screws 36.

Water is led into the water chamber via a duct 32 and hot water andsteam are passed out to the boiler and tank (not shown) through separateconnections 33.

The elbows 3| are mounted on the end wall I by means of flanges 35 andbolts and nuts, the flange 38 of the liners or wear plates 31 beingsecured at the same time between flange 35 and wall I.

Power may be applied to shaft l l in any suitable Way, as by a knownthermostatically-controlled motor (not shown), belted to pulley 39 orconnected thereto in any other approved way.

A perforate baffle 36 is located over the entrant end of each ashdischarging worm or screw 2| at the level of the grate wall 8 (see Figs.1 and 3) and prevents too rapid ash removal at this place.

A suitable air entrance 4!) is provided in one of the walls to admit airbelow the grates, and the walls are strengthened by suitable anglebraces 4| and 42.

It is to be understood that the water sections of the boiler (not shown)are built above the walls I and 2 and are secured in any suitable way tothe flanges formed by the upper angles 42.

Operation Assume that the apparatus is in place in a furnace whose smokepipe is connected to a suitable stack so as to create a natural draft.The worm I! carries the coal from hopper it into the central channel 3,4, the coal being forced upwardly along the length of the channel by thecombined action of the worm l'l, segments l2, and inclined baffie l3.

As the coal rises to the top of the central channel it spills over intothe side channels where it is ignited and burns. After the apparatus hasbeen started up and is running normally, the ignited coal will lie abovethe level of shafts 24, while the ash will lie below the same. (Ofcourse there is no fine line of demarcation between the burning coal andthe ash.) The speed of the apparatus is adjusted so that the fire bed ofcoal is maintained at a uniform depth and only enough ashes are passedout as will maintain the same. Any clinkers which may form will be atthe bottom of the fire zone and will be broken up by the fins 25 onshafts 24.

The air for supporting combustion is drawn in to the side channelsthrough the gratings B and 9 from the bottom of the box by the naturalsuction of the chimney, although a forced draft may be employed ifdesired. With natural draft, i. e., a negative pressure above the fireand atmospheric pressure below the same, less fly-ash will be passedthrough the furnace into the chimney than with blower draft, i. e.,above atmospheric pressure beneath the fire.

Since the fire zones of the apparatus lie along the walls 5, ample heatwill be applied to the same to heat the water within the water chamberto the degree desired, even with the fire checked.

In mild weather only half the fire need be kept up. By loosening the setscrew 30 of one gear 23, that side of the apparatus will not dischargeash and soon the ash will build up to a level where the fire on thatside will become extinguished and the other side of the apparatus alonewill function.

Attention is called to the fact that the side channels are deeper downthan the central channel, and they may be very much deeper if desired.For instance, in a furnace having a considerable space in the fire boxabove the usual grate level, the central channel and coal feeder may belocated well up in the fire box space, while the ash removers 19 may belocated near the bottom of the ash pit or well below the usual gratelevel.

Further, as indicated by broken lines in Fig. 4, the fire zone ofburning coal may be and usually is located up level with the fluidjacket zone a of the boiler so that the heat and products of combustionof the coal will be directed angularly outwardly and upwardly (seearrows b, Fig. 4) against the wall of the furnace to heat directly thefluid in the jacket zone a, as well as that above the crown a.

From the foregoing description, taken in connection with theaccompanying drawings, it is thought that the construction, operationand advantages of the invention will be clear to those skilled in theart.

What I claim is:

1. In apparatus of the class described, a box comprising end and sidewalls, a longitudinally disposed double walled body located in said boxand enclosing a water chamber, said body comprising a centrallongitudinal channel and outwardly-downwardly inclined imperforatedwalls, grates U-shaped in cross-section extending parallel to said bodyand having a perforate side wall constituting downward extensions ofsaid outwardy-downwardly inclined walls, a coal supply source, means toconvey coal from said source into and along the bottom of said centralchannel and upwardly therein to spill over the sides onto saidoutwardly-downwardly inclined walls, said grates each also including animperforate bottom and a second perforate wall, said perforate walls andimperforate bottom of the grates constituting side channels into whichthe coal spills from said central channel, means to remove ashes fromsaid side channels, and means to pass water into said water chamber andto pass water and steam out of the same.

2. In apparatus of the class described, a box comprising end and sidewalls, a longitudinally disposed double walled body located in said boxand enclosing a water chamber, said body comprising a centrallongitudinal channel and outwardly-downwardly inclined imperforatedwalls, grates U-shaped in cross-section extending parallel to said bodyand having a perforate side wall constituting downward extensions ofsaid outwardly-downwardly inclined walls, a coal supply source, means toconvey coal from said source into and along the bottom of said centralchannel and upwardly therein to spill over the sides onto saidoutwardly-downwardly inclined walls, said grates each also including animperforate bottom and a second perforate Wall, said perforate walls andimperforate bottom of the grates constituting side channels into whichthe coal spills from said central channel, means to remove ashes fromsaid side channels, means to pass water into said water chamber and topass water and steam out of the same, and other means to break clinkersforming in said side channels.

3. In apparatus of the character described, a box composed of side andend walls, a water heating vessel having a pair of central separatedwalls and stationary downwardly-outwardly divergent walls at the sides,said central walls being joined at the bottom, a coal infeed shaft withworm and worm segments to pass coal into the channel formed by saidcentral separated walls, coal burning channels at each side of saidcentral walls and including perforated grates constituting channels ofU-shape in cross section, the inner walls of said grates comprisingdownward extensions of said downwardly-outwardly divergent walls, ashremoval shafts in said channels at the bottom, said ash removal shaftsbeing located at a lower level than said coal infeed shaft, rotatableclinker breaker shafts in said last named channels above said ashremoval shafts, and power transmitting connections between said shafts.

4. In apparatus of the character described, a box composed of side andend walls, a water heating vessel having a pair of central separatedwalls and stationary downwardly-outwardly divergent walls at the sides,said central walk being joined at the bottom, a coal infeed shaft withworm and worm segments to pass coal into the channel formed by saidcentral separated walls, coal burning channels at each side of saidcentral walls and including perforated grates constituting channels ofU-shape in cross section, the inner walls of said grates comprisingdownward extensions of said downwardly-outwardly divergent walls, ashremoval shafts in said channels at the bottom, said ash removal shaftsbeing located at a lower level than said coal infeed shaft, rotatableclinker breaker shafts in said last named channels above said ashremoval shafts, power transmitting connections between said shafts, andmeans whereby said power transmitting connections may be operativelydisconnected from the ash removal shafts and clinker breaker shafts atwill.

5. In apparatus of the class described, a box composed of side and endwalls, a transverse zi zag partition extending in said box from one wallto the opposite wall and formed to provide a central longitudinal opentop channel and two side longitudinal open top channels, the bottoms ofsaid channels being concaved, the walls of the central channel beingimperforate, the walls of the side channels adjacent the central channelbeing imperforate at their upper portion and perforate at their lowerportions, a coal feed shaft at the bottom of the central channel, ashremover shafts at the bottoms of the side channels, the side channelsbeing deeper than the central channel, clinker breaker shafts in saidside channels at about the level of the top of the perforate portions ofthe side channels walls, and means to admit air into said box below saidpartition.

6. In apparatus of the class described, a box composed of side and endwalls, a transverse zigzag partition extending in said box from one wallto the opposite wall and formed to provide a central longitudinal opentop channel and two side longitudinal open top channels, the bottoms ofsaid channels being concaved, the walls of the central channel beingimperforate, the walls of the side channels adjacent the central channelbeing imperforate at their upper portion and perforate at their lowerportions, a coal feed shaft at the bottom of the central channel, ashremover shafts at the bottoms of the side channels, clinker breakershafts in said side channels at about the level of the top of theperforate portions of the side channels walls, and means to admit airinto said box below said Partition.

'7. In apparatus of the class described, a box composed of side and endwalls, a transverse zigzag partition extending in said box from one wallto the opposite wall and formed to provide a central longitudinal opentop channel'and two side longitudinal open top channels, the bottoms ofsaid channels being concaved, the walls of the central channel beingimperforate, the walls of the side channels adjacent the central channelbeing imperforate at their upper portion and perforate at their lowerportions, a coal feed shaft at the bottom of the central channel, ashremover shafts at the bottoms of the side channels, clinker breakershafts in said side channels at about the level of the top of theperforate portions of the side channels walls, and means to admit airinto said box below said partition, the side walls of the centralchannel being approximately parallel and the side walls of the sidechannels being divergent upwardly.

8. In apparatus of the class described, a box composed of side and endwalls, a transverse zig-zag partition extending in said box from onewall to the opposite wall and formed to provide a central longitudinalopen top channel and two side longitudinal open top channels, thebottoms of said channels being concaved, the walls of the centralchannel being imperforate, the walls of the side channels adjacent thecentral channel being imperforate at their upper portion and perforateat their lower portions, a coal feed shaft at the bottom of the centralchannel, ash remover shafts at the bottoms of the side channels, clinkerbreaker shafts in said side channels at about the level of the top ofthe perforate portions of the side channels walls, means to admit airinto said box below said partition, a bottom wall joining one of saidimperforate portions with the other and spaced from the walls of thecentral channel to constitute therewith a water space, and means to leadwater into and from said water space.

9. In apparatus of the class described, a box composed of side and endwalls, a transverse zig-zag partition extending in said box from onewall to the opposite wall and formed to provide a central longitudinalopen top channel and two side longitudinal open top channels, thebottoms of said channels being concaved, the walls of the centralchannel being imperforate, the walls of the side channels adjacent thecentral channel being imperforate at their upper portion and perforateat their lower portions, a coal feed shaft at the bottom of the centralchannel, ash remover shafts at the bottoms of the side channels, clinkerbreaker shafts in said side channels at about the level of the top ofthe perforate portions of the side channels walls, means to admit airinto said box below said partition, the side walls of the centralchannel being approximately parallel and the side walls of the sidechannels being divergent upwardly, a bottom wall joining one of saidimperforate portions with the other and spaced from the walls of thecentral channel to constitute therewith a water space, and means to leadwater into and from said water space.

10. In apparatus of the class described, a box composed of side and endwalls, a transverse zig-zag partition extending in said box from oneWall to the opposite Wall and formed to provide a central longitudinalopen top channel and. two side longitudinal open top channels, the wallsof the central channel being imperforate, the walls of the side channelsadjacent the central channel being imperforate at their upper portionand perforate at their lower portions, a coal feed shaft at the bottomof the central channel, ash remover shafts at the bottoms of the sidechan nels, clinker breaker shafts in said side channels at about thelevel of the top of the perforate portions of the side channelswalls,and means to admit air into said box below said partition.

11. In apparatus of the class described, a box composed of side and endwalls, a transverse zig-zag partition extending in said box from onewall to the opposite wall and formed to provide a central longitudinalopen top channel and two side longitudinal open top channels, the wallsof the central channel being imperforate, the walls of the side channelsadjacent the central channel being imperforate at their upper portionand perforate at their lower portions, a coal feed shaft at the bottomof the central channel, ash remover shafts at the bottoms of the sidechannels, clinker breaker shafts in said side channels at about thelevel of the top of the perforate portions of th side channels walls,means to admit air into said box below said partition, a bottom walljoining one of said imperforate portions with the other and spaced fromthe walls of the central channel to constitute therewith a water space,and means to lead water into and from said water space.

12. In apparatus of the class described, a box composed of side and endWalls, a transverse zig-gaz partition extending in said box from onewall to the opposite wall and formed to provide a central longitudinalopen top channel and two side longitudinal open top channels, the wallsof the central channel being imperforate, the walls of the side channelsadjacent the central channel being imperforate at their upper portionand perforate at their lower portions, a coal feed shaft at the bottomof the central channel, ash remover shafts at the bottoms of the sidechannels, clinker breaker shafts in said side channels above said ashremover shafts, and means to admit air into said box below saidpartition, said coal feed shaft including coal lifter blades located atintervals apart within the central longitudinal channel.

13. In apparatus of the class described, a box composed of side and endwalls, a transverse zig-zag partition extending in said box from onewall to the opposite wall and formed to provide a central longitudinalopen top channel and two side longitudinal open top channels, the wallsof the central channel being imperforate, the walls of the side channelsadjacent the central channel being imperforate at their upper portionand perforate at their lower portions, a coal feed shaft at the bottomof the central channel, ash remover shafts at the bottoms of the sidechannels, means to admit air into said box below said partition, clinkerbreaker shafts in said side channels above said ash remover shafts, saidcoal feed shaft including coal lifter blades located at intervals apartwithin the central longitudinal channel, and a coal-conveying ductoutside the box and communicating with one end of said centrallongitudinal channel, said coal feed shaft having a worm within saidcoal-conveying duct.

JOSEPH T. NORMAN.

